... this is the largest decrease ever recorded by Rightmove at this time of year, and a lead indicator of a slower market in the second half of 2014. The price fall has been exacerbated by London recording a 5.9% drop, which is the largest of three consecutive monthly falls.

Here are the data in charts.

This average price tracking line shows a clear decline over recent months:

Here's the same data expressed in terms of percentage growth. Note that this August's seasonal dip is worse than 2013:

People are selling far fewer properties now than they were last year — perhaps because sellers can't get the prices they want.

If you want evidence that London is in a full-scale collapse, here's Rightmove's current chart of the best-performing neighborhoods in the city. They're all down:

Rightmove's staff and estate agent network had several explanations for the news: They attributed the declines to the season, the Bank of England's talk about raising interest rates soon, and buyers being priced out of the market.